Conversion of highly volatile paraffins to liquid hydrocarbons containing aromatics



CONVERSION HIGHLY VOLATILE PARAFFINS TO LIQUID HYDROCARBONS CONTAINING AROMATICS Lewis E. Drehman and E. 0. Box, Jr., Bartlesville, kla.,

assignors to Phillips Petroleum Company, a corporation of Delaware Application May 9, 1957, Serial No. 658,101

9 Claims. (Cl. 260-673) This invention relates to the catalytic conversion of highly volatile hydrocarbons to normally liquid hydrocarbons. In one of its aspects, it relates to a process for converting parafiin hydrocarbon containing three to five carbon atoms per molecule to normally liquid hydrocarbon containing appreciable amounts of aromatics. In another aspect, the invention relates to a catalyst for the conversion of highly volatile parafiin hydrocarbons to aromatic hydrocarbons.

It is known that halogens catalyze the cracking of light hydrocarbons to produce lower molecular weight unsaturated hydrocarbons. Iodine has been used as a catalyst for the destructive distillation of high boiling hydrocarbons into lower boiling hydrocarbons.

In accordance with the present invention, it has been discovered that small amounts of iodine or hydrogen iodide catalyze the conversion of highly volatile hydrocarbons to liquid hydrocarbons containing appreciable amounts of aromatics under reaction conditions of elevated temperature and pressure. We have found that cracking of the hydrocarbons is decreased when iodine or hydrogen iodide is used as a catalyst as compared to conventional thermal cracking and this is surprising in view of the known practices of the prior art. We have found that by using iodine or hydrogen iodide as the catalyst in the conversion of propane, butane, or pentane, that the yield of aromatics is greatly increased, as compared to the reaction with chlorine or bromine as the catalyst or with no catalyst.

It is, therefore, an object of this invention to provide an improved process for the conversion of low boiling hydrocarbons to higher boiling hydrocarbons.

It is also an object of this invention to provide a method for increasing the yield of aromatics wherein low boiling hydrocarbons are converted into higher boiling hydrocarbons.

Another object of this invention is to provide a catalyst for improving the yield of aromatics in a process for converting low boiling hydrocarbons into higher boiling hydrocarbons.

Other objects and advantages of this invention will be apparent to one skilled in the art upon study of the disclosure of this invention including the appended drawing wherein a flow sheet diagrammatically illustrates one embodiment of this invention.

The conversion of paraflin hydrocarbons containing three to five carbon atoms per molecule to normally liquid hydrocarbons results in a considerable increase in the ar0- matic content of the products boiling in the gasoline range when the reaction is conducted in the presence of about 0.01 mole percent to about 1 mol percent of iodine or hydrogen iodide. The reaction is conducted at a pressure in the range of about 1000 to about 3000 p.s.i. and at a temperature in the range of about 900 to 1100 F. The time of reaction of the hydrocarbons is correlated with the temperature of the reaction so as to provide optimum conversion and the time of reaction is usually maintained in the range of about 0.1 minute to about minutes.

2,881,229 Patented Apr. 7, 1959 ice.-

Referring now to thedrawing, the invention will be described as applied to the conversion of normal butane with iodine as the catalyst. 'Butane gas is introduced into the process via conduit 10Iand the catalyst in vapor form is'admixed with the butane feed in conduit 10 and is introduced via conduit 9'. The gaseous mixture of butane and iodine is compressed in compressor 11 and passed to reactor 12 where the'temperature is raised to about 950 F. for a reaction time ofabout 6 minutes. Reactor 12 can be a conventional furnace containing coils of tubing or any known heat exchange device. The efiluent from reactor 12 is passed through cooler 13 and thence via conduit 14 to a wash chamber 15." Wash chamber 15 contains water or an aqueous solution of sodium sulfite or I other known solvent for iodine. Waste aqueous solution containing iodine catalyst is withdrawn from a wash vessel 15 via'conduit 16 and make-up water or solution is provided via conduit 17. Catalyst-free hydrocarbon is passed viac'onduit 18 to depro'panizer19 where propane and lightergases, together with some heavier material passes overhead via"conduitf2 1 through cooler 22 and conduit 23 'toaccumulator-separator 24; Propane and lighter gases are removed via conduit 25 and heavier hydrocarbons which have condensed in accumulator-separator 24 are passed via conduit 26, pump 27, and conduit 28 to the top of depropanizer 19 as reflux liquid. Hydrocarbons heavier than propane are withdrawn from the bottom of depropanizer 19 and are passed via conduit 29 to debutanizer 31 where butane is removed overhead as a vapor and is recycled to feed conduit 10 via conduit 32. Liquid hydrocarbon product is Withdrawn from the bottom of debutanizer 31 via conduit 33 and is removed for further processing or use.

The amount of iodine or hydrogen iodide employed as a catalyst is soluble in the hydrocarbons being processed so that the catalyst can be added to the liquid hydrocarbon and the resulting mixture vaporized or the catalyst can be vaporized and added as a vapor to the vaporized hydrocarbon. The catalyst is recovered from the reactor efiluent by means of an aqueous Wash or an aqueous solution capable of dissolving iodine. Examples of aqueous solutions suitable for wash materials include sodium sulfite, carbon disulfide, and the like.

The following example will illustrate the invention but is not to be interpreted as limiting the invention. Normal butane was subjected to the conditions set forth in the following Table I and the data therein recorded show the results obtained.

Table l Run No 1 2 3 4 Catalyst I: OHBra CHCls M01 percent of catalyst in feed 0. 2 2. 3 2. 3 Temperature, F 950 950 850 975 Pressure, p.s.i 1, 080 1,060 1,030 2, 330 Reaction time, minutes 5. 6 3. 1 4 Composition of 05+, liq. vol. percen O5, temp. range of cut, F.

50-104 11 25. 5 22 26 Ga, temp. range of cut, F.

122-156 14 36 25 26. 5 O7, temp. range of cut, F.

156-212 7. 5 21. E 27 21. 5 Benzene, temp. range of cut,

F. 167-185 4 1 Ca, temp. range of cut, F. 212- 257 10 17 9 7.5 Toluene, temp. range of cut, F.

230239 16 3 C9, temp. range of cut, F. 257+ 20. 5 16. 6 14. 6 0a Aromatics, temp. range of cut, F. 276-293 17 Butane conversion, percent 22. 2 5.1 40. 2 Gasoline yield, percent of 04 converted 24 23. 2 48. 8 36. 5 Aromatic content of gasoline 37 Trace Trace 4 Reasonable variations and'modifications are possible within the scope of the disclosure of the present invention, the essence of which is the discovery that iodine or hydro gen iodide is an etfective catalyst for the conversion of light hydrocarbons to aromatic hydrocarbons.

That which is claimcd'is: a

l. A processfor converting a normal paraflin hydrocarbon having 3 to 5 carbon atoms per molecule into normally liquid hydrocarbons containing appreciable amounts of aromatic hydrocarbons which comprises contacting said parafiin hydrocarbon with a catalyst consisting essentially of a material of the group consisting of hydrogen iodide and iodine at a temperature in the range of about 900 to about 1100 F., and a pressure in the range of about 1000 to about 3000 p.s.i. for a time in the range of 0.1 minute to minutes.

2 The process of claim 1 wherein the paraffin hydrocarbon is propane.

3. The process of claim 1 wherein the parafiin hydrocarbon is butane.

4. The process of claim 1 wherein the paraflin hydrocarbon is pentane.

5. The process of claim 1 wherein the catalyst is hydrogen iodide.

6. The process of claim 1 wherein the catalyst is iodine. 7. A process for converting a normal parafiin hydrocarbon having 3 to 5 carbon atoms per molecule into normally liquid hydrocarbons containing appreciable amounts of aromatic hydrocarbons which comprises passing said paratfin hydrocarbon containing from 0.01 to 1 mol percent of a catalyst consisting essentially of a material of the group consisting of hydrogen iodide and iodine to a reaction zone maintained at a temperature of about 950 F. and a pressure of about 1100 p.s.i.; maintaining said by drocarbon in said reaction zone for about 5 to 6 minutes; passing the efiluent from the reaction zone through an aqueous wash medium to remove catalyst; removing propane and lighter gases from the washed hydrocarbon mixture; removing butane from the hydrocarbon mixture; and recovering liquid hydrocarbons containing an appreciable amount of aromatic hydrocarbons as a product of the process.

8. The process of claim 7 wherein the catalyst is iodine.

9. The process of claim 7 wherein the catalyst is hydrogen iodide.

References Cited in the file of this patent UNITED STATES PATENTS 1,925,421 Van Peski Sept. 5, 1953 FOREIGN PATENTS 849,804 France Dec. 2, 1939 

1. A PROCESS FOR CONVERTING A NORMAL PARAFFIN HYDROCARBON HAVING 3 TO 5 CARBON ATOMS PER MOLECULE INTO NORMALLY LIQUID HYDROCARBONS CONTAINING APPRECIABLE AMOUNTS OF AROMATIC HYDROCARBONS WHICH COMPRISES CONTACTING SAID PARAFFIN HYDROCARBON WITH CATALYST CONSISTING ESSENTIALLY OF A MATERIAL OF THE GROUP CONSISTING OF HYDROGEN IODIDE AND IODINE AT A TEMPERATURE OIN THE RANGE OF ABOUT 900 TO ABOUT 1100*F., AND A PRESSURE IN THE RANGE OF ABOUT 1000 TO ABOUT 3000 P.S.I. FOR A TIME IN THE RANGE OF 0.1 MINUTE TO 10 MINUTES. 